Gastrointestinal Stromal Tumor in Monozygotic Twins Shows Distinct Mutational Status: A Case Report.

BACKGROUND Gastrointestinal stromal tumors (GISTs) are rare mesenchymal cancers that affect the gastrointestinal tract and are most often located in the stomach and proximal small intestine. The most common molecular genetic abnormalities underlying GIST carcinogenesis are mutations in the tyrosine kinase gene (KIT) and in the platelet-derived growth factor receptor alpha (PDGFRA) gene. To the best of our knowledge, no cases have been reported so far of synchronous diagnosis of GIST in 2 monozygotic twins presenting with clinical and morphological features of sporadic disease. CASE REPORT This report presents the cases of 2 monozygotic twin sisters who were diagnosed with GIST at the same age and who had different KIT exon 11 tumor mutational statuses. In the current report, the screening examination that led to early detection of GIST in one of the sisters was not motivated by any symptom, but by a GIST diagnosis in her twin a few days before. The literature was reviewed for pathological and molecular features associated with prognosis and treatment response. Furthermore, we identified identical genotypes of KIT and PDGFRA polymorphisms in the DNA of both tumors that might be present in the germline DNA. The present case supports the implementation of specific cancer screening in the context of monozygotic twins, regardless of identification of the genetic components involved. CONCLUSIONS Our report suggests that monozygotic twins with GIST can have different mutational statuses for KIT and PDGFRA. Referral for special screening should be considered for individuals who have a monozygotic twin diagnosed with cancer.

Mutational Profile and New IASLC/ATS/ERS Classification Provide Additional Prognostic Information about Lung Adenocarcinoma: A Study of 125 Patients from Brazil.

AIM: To show additional prognostic information about the mutational profile and new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society (IASLC/ATS/ERS) classification of adenocarcinoma (ADC) in patients without epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor treatments. METHODS: In human lung ADC patients (n = 125), including 24 lepidic, 67 acinar, 23 papillary, and 11 solid predominant subtypes, EGFR and KRAS were sequenced, and anaplastic lymphoma kinase (ALK) rearrangements were screened using fluorescence in situ hybridization (FISH). RESULTS: EGFR was mutated in 21.6% of patients with 19.57% showing a mean expression. The most frequent EGFR mutation was a deletion in exon 19, followed by an L858R amino acid substitution in exon 21. KRAS was mutated in 26.4% of patients with 50% displaying mean expression. ALK rearrangement was detected in 6 patients (4.8%). Predominant acinar ADC was strongly associated with EGFR and KRAS mutation. Clinical stage, lymph node metastases, and EGFR mutation in exon 18 showed a significant difference in disease-free and overall survival, but only a trend significance for EGFR and KRAS mutations. Multivariate analysis revealed that men aged >71 years, with a history of smoking (<72 packs/year), clinical stage I/II, and acinar histologic subtype presented better survival than women aged ≤ 71 years, with a history of smoking (>72 packs/year), and having a predominant solid ADC and EGFR mutation in exon 18. CONCLUSIONS: These results indicate that the mutational profile and new IASLC/ATS/ERS classification provide additional prognostic information about lung ADC.

Involvement of signaling molecules in the prediction of response to imatinib treatment in metastatic GIST patients.

Imatinib therapy has undoubtedly contributed to the treatment of metastatic gastrointestinal stromal (GIST) tumors that were previously untreatable. However, disease progression during treatment with tyrosine kinase inhibitors remains an issue in clinical practice not fully explained by KIT and PDGFRA mutation status. We investigated the role of three important signaling molecules (insulin-like growth factor 1 receptor [IGF1R], protein kinase C-θ [PKCθ], and Raf kinase inhibitor protein [RKIP]) that have been implicated in GIST pathogenesis as potential biomarkers for prediction of response to imatinib treatment. We retrospectively reviewed 76 patients with metastatic GIST submitted to imatinib treatment between 2002 and 2007, and analyzed 63 of them. Insulin-like growth factor 1, total PKCθ, phosphorylated PKCθ, and RKIP immunohistochemical expression were correlated with objective response to imatinib treatment and progression-free and overall survival. Median follow-up was 31.2 mo (95% confidence interval, 26.3-36.1 mo). There was a statistically significant association between IGF1R expression and type of response to imatinib treatment (P = 0.05)-that is, higher IGF1R expression was related to lower objective response. However, IGF1R higher expression did not affect progression-free and overall survival. Insulin-like growth factor 1, but not PKCθ and RKIP, emerges as a potential biomarker for prediction of response to imatinib treatment in metastatic GISTs. Validation studies are warranted.